The diagram shows the earth’s position in its orbit around the sun at the beginning of each season. The
moon is shown at various positions as it revolves around the earth. Assume the line from A to C is the
1. The earth’s orbit around
the sun is best described as
a. A perfect circle
b. An oblate spheroid
c. A very eccentric ellipse
d. A slightly eccentric
2. The phase of the moon at
A would be
3. Determine the value of the semi major axis “a”.
4. If e= 0.0167, determine the value of the focus length “c”.
5. Determine the value of the semi major axis “b”.
6. Draw a better picture of earth’s orbit of the sun which includes “a’, “b” and “c”. Label the approximate
season that would correspond to A, B, C, and D. Remember that the earth’s is closest to the sun on January
7th and that would be winter in the northern hemisphere.
7. Calculate the Gravitation Force between the earth and sun at the following locations
8. Calculate the speed of Earth’s orbit at the following locations
9. Determine the value of the Kepler’s 3rd law constant for the earth in m3/s2.
The diagram represents a model of the orbit of a moon around a planet. Points A, B, C, and D indicate
the four positions of the moon in its orbit. Points F1 and F2 are focal points of the orbit.
1. If the moon takes 6.8 days
to move from point A to point B, the best
estimate for the time required for one
a. 20 days
b. 27 days
c. 34 days
d. 41 days
2. When viewed from the
planet, the moon would have the greatest
apparent diameter(look biggest) at point
a. A b. B c. C d. D
3. From which position in the
moon’s orbit does the full moon phase
occur? a. A b. B c. C d. D
5. If the distance from F1 to F2 is 42000 km and the major axis distance from A to C is 768000 km, what is the
eccentricity of the moon’s orbit?
6. Determine the value of the semi minor axis length “b”.
7. Label “a”, “b”, and “c” distances in the diagram above. Also label the distance from F2 to B with
“a”, “b”, or “c”
8. As the moon moves from point D to point B, the force of gravitational attraction between the moon and
a. Increases only b. decreases only c. increases then decreases d. decreases then increases
9. Calculate the Gravitation Force between the earth and sun at the following locations
10. Calculate the speed of Earth’s orbit at the following locations
11. Determine the value of the Kepler’s 3rd law constant for the moon in m3/s2.